The present invention relates to a system for the continuous production of high purity silica, related methods, and the silica product produced therefrom. The invention finds particular application in conjunction with the production of ultra high purity synthetic silica, and will be described with particular reference thereto. However, it is to be appreciated that the present invention is also amenable to other like applications.
Exclusion of oxygen during high temperature processing i.e., anoxic processing, of synthetic silica enables production of a silica material with two important properties: ultra high purity, and low hydroxyl content. Previously, anoxic processing methods have been limited to batch reactors in which rigorous exclusion of ambient oxygen-bearing gasses can be accomplished. Although somewhat satisfactory, batch reactors are limited in their ability to economically produce a price competitive silica product. Accordingly, it would be desirable to provide a continuous anoxic reactor, related system and process for producing an ultra high purity synthetic silica product.
Due to the relatively high temperatures involved in a silica purification process, it is generally quite difficult to exclude oxygen from the reaction environment. A prime source of oxygen is from ambient air which tends to be drawn into the reactor as a result of the draft resulting from the high temperatures within the interior of the reactor. This difficulty in sealing the interior of the reactor from the atmosphere is further compounded due to the rotation of the reactor, which is typically quartz glass. Accordingly, a need exists for a strategy by which to exclude oxygen or at least significantly prevent entry of air, into a rotating high temperature reactor.
In addition, in the production of synthetic silica, it is necessary to produce reducing conditions in the reactor in order to form stable volatile chlorides that can be subsequently removed. It is difficult to maintain sufficiently reducing conditions in a rotating high temperature system. Accordingly, it would be desirable to provide a rotating high temperature reactor that can maintain sufficiently reducing conditions such that certain chlorides present in the production of synthetic silica can be readily removed from the reactor.